1987年发表的报告《我们共同的未来》（Our Common Future）成为了一个转折点。在这份报告中，世界环境与发展委员会总结了四年来围绕可持续发展概念的研究成果。这份历史性文件对于建筑环境在实现可持续发展方面的作用仅仅一笔带过。不过，建筑行业却是气候适应能力、公共卫生、生命安全、热舒适度和能源负担能力等诸多问题的核心所在。
可持续发展不是一成不变的概念，而是随着时间的发展在变化。20世纪70年代，石油危机促使人们开始尝试化石燃料的替代品。如今，我们面临的最紧迫的问题是气候变化，这已成为驱动变革的一股重要力量，建筑领域在气候变化的推动下实现了重要的技术发展。但要实现可持续的建筑环境，还需要在更大范围内移易社会文化，例如，更新学校课程以及要求资深从业者和学者掌握新的技能和知识。
“对于人类能否在生物圈可承受范围内继续生存下去，工程师、建筑师、规划师负有很大责任”
建筑物的建造、运营和维护都需要消耗大量能源和资源。世界绿色建筑委员会的数据显示，建筑环境占全球碳排放量的39%，其中28%都与所谓的“建筑运营”本身（包括供暖、制冷、通风和照明）所需的能源有关，另外11%与建造施工有关。由此可见，对于人类能否在生物圈可承受范围内继续生存下去，工程师、建筑师、规划师以及参与建筑设计、管理和施工的专业人员负有很大责任。
© 伊万·巴恩（Iwan Baan）位于印度南部特里凡得琅的发展研究中心（1973 年）由劳里·贝克设计，这位设计师是低成本环境可持续建筑的先驱之一。
可持续建筑的理念与热泵、太阳能集热器和太阳能电池板等技术密切相关。不过，向可持续设计的过渡还涉及在建筑设计和城市化建设方面采用气候意识更强的方法。“被动式设计”方法着眼于通过基本决策（例如，建筑物的朝向、善用玻璃和遮阳物）帮助建筑物更好地适应当地气候。这种做法有助于减轻、有时甚至可以消除建筑物对供暖和制冷系统的依赖。
被动式设计原理不是新生事物，在传统建筑中可以明显看到这种设计，古代文献中也有提及。希腊著名哲学家苏格拉底（Socrates）曾阐述过气候与建筑物的形状及朝向之间的关系，古罗马建筑师维特鲁威（Vitrivius）也曾针对不同气候条件下的建筑设计给出了详细的指导。
如今，现代技术帮助这种古老的气候响应型设计传统走向了复兴。德国“被动式房屋”（PassivHaus）标准就是典型的被动式设计，这套标准着眼于通过气密性、高隔热性能和三层玻璃窗来优化能源效率。被动式房屋还采用了机械通风和热回收等“主动”技术；事实上，可持续建筑极少采用纯被动式设计。大多数建筑都会配备通风、供暖、制冷和可再生能源发电等主动系统。
在炎热气候下，首要问题是防止热能进入室内和减少使用机械空调。在摩洛哥的菲斯和叙利亚的阿勒颇等中东和北非古城中，可以看到适应炎热气候的一些传统建筑设计。这些建筑的特点是墙壁厚、门窗小、庭院和街道皆有遮蔽物。在16世纪的也门古城希巴姆，高层建筑也采用了同样的建筑原理。
这些特点与阿联酋迪拜、卡塔尔多哈等现代沙漠城市的建筑和城市规划形成了鲜明对比，后者放眼皆是现代化摩天大楼。即便是配备了外部遮阳设施或旨在减少吸收太阳辐射的特殊玻璃，这些高楼依然需要大量机械冷却。不过，阿拉伯半岛也在探索其他的发展模式。马斯达尔是阿布扎比在2008年开工建设的一座新城，这座城市是现代城市设计的一次尝试，既借鉴了传统的气候设计原理，又融入了可再生能源技术。
© 罗兰·哈博 位于德国斯图加特的 R128 宅邸是一座实验性的独栋住宅，由德国建筑师沃纳·索贝克（Werner Sobek）在 2000 年设计。它几乎全部都可以回收利用，没有使用化石燃料能源，也不排放温室气体。
建筑材料的隐性排放
建筑业的碳排放量大部分来自建筑物的运营，但建筑施工的碳足迹同样不容小觑。建筑物的“嵌入碳”是指原材料开采、加工和运输过程中产生的碳排放。钢材、钢筋混凝土和砖都是碳密集度最高的材料。水泥行业的碳排放量约占全球排放量的8%；建筑业对钢筋混凝土的需求很大，是这项建材的消费大户。
有多种方法可以减少嵌入碳，例如，更有效地利用各种材料、脱碳生产和采用低碳替代材料。低碳材料促使人们更多地关注自然资源，这包括木材和芦苇等植物基材料，以及就地取材的土建筑技术，例如，夯土、压缩土块或日晒黏土砖。2021年，一家瑞典公司推出了利用可再生能源电力生产的氢制造低碳钢的方法。
近年来世界各地的建筑工程表明，在高层建筑上使用工程木材有助于减少对钢材和混凝土的依赖，例如，挪威布鲁蒙达尔的米约萨大厦高达85.4米，全部采用胶合木和交错层压木材建成。
从线性经济到循环经济
减少材料消耗是实现可持续发展的另一个关键目标。为此，需要摒弃建筑材料使用后便丢弃的线性经济，改为重复使用和回收再利用的循环经济。在循环经济中，通过拆除得到的材料不再作为废物处理，而是作为资源得到利用。这就要求建筑系统在设计上要做到易于拆卸，以便重复使用。
“减少材料消耗是实现可持续发展的关键”
英国、马来西亚、中国和日本的木结构建筑是可拆卸结构的传统典范。当代建筑领域也出现了很多类似项目，例如，2017年在加拿大温哥华建成了由40个单元组成的模块化临时住房建筑（“车站街220号”），以及用来举办大型体育赛事的可拆除运动场。可拆卸结构的另一个例子是美国基兰-汀布莱克建筑事务所设计的“火炬松别墅”，这种混合能源住宅由预制构件组装而成，使用简单的手动工具即可完成现场组装和拆卸。
可持续做法还涉及对建筑物及建筑材料的长期管理责任，包括延续几代人的创建、运营、维护和更新，也涉及现有建筑的保留和适应性再利用，这体现出了可持续发展与建筑保护的交汇。
重复使用，避免破坏
适应性再利用避免了拆除建筑，同时还可以通过翻修改造，减少能源消耗。人们非常重视保护具有历史意义的建筑，不过大多数建筑物并无历史意义，许多建筑仅仅使用了30年至50年就被拆除了。但全球环境危机迫使人们对这种做法提出质疑。由此出现的问题是，是否应当将“气候意义”作为一项新的保护标准，与文化意义和历史意义并列。
在法国，建筑师安妮·拉卡顿（Anne Lacaton）和让-菲利普·瓦萨尔（Jean-Philippe Vassal）让人们看到，更新改造邻里和睦的战后住宅区可以替代拆除方案。在德国弗莱堡，巴格街50号旧居改造项目重新整修了一座建于20世纪60年代的16层塔楼，将大楼的供暖能耗降低了80%。
欧洲和北美的许多项目往往涉及技术复杂且造价昂贵的解决方案，但可持续设计的基本原理是通用的，可以适用于不同的社会经济条件和气候环境。在20世纪，印度建筑师劳里·贝克（Laurie Baker，1917-2007年）和埃及建筑师哈桑·法蒂（Hassan Fathy，1900-1989年）致力于复兴传统建筑，以建造适应气候的经济适用房。近年来，布基纳法索裔德国建筑师迪埃贝多·弗朗西斯·凯雷（Diébédo Francis Kéré）和巴基斯坦建筑师亚斯敏·拉里（Yasmeen Lari）主张回归乡土建筑法则，传达出全球南方可持续建筑话语。
正在兴起的这股乡土建筑之风借鉴了建筑物理学的基本原理，它表明可持续建筑既不依赖复杂的技术解决方案，也不依赖与未来技术发明有关的遥不可及的目标。可持续建筑靠的是建筑师的才智，要求建筑师能够巧妙利用现有及新兴的大量技术和原理。
Architects and urban planners at the forefront
The energy-intensive building sector alone accounts for 39 per cent of global carbon emissions. In light of this, a fundamental transformation is the only option for the sector to become eco-responsible.
Innovative technologies, the role of recycling in the built environment, the use of natural materials, and construction techniques adapted to local conditions are some of the paths to be explored in the quest for more sustainable architecture.
Henrik Schoenefeldt
Professor for Sustainability in Architectural Heritage at University of Kent School of Architecture and Planning (United Kingdom).
Published in 1987, a report called Our Common Future was a turning point. In this document, the World Commission on Environment and Development summarized the findings of a four-year inquiry into the concept of sustainable development. The role of the built environment in achieving sustainable development is only briefly noted in this historic document. However, the building sector is at the centre of questions surrounding climate resilience, public health, safety, thermal comfort, and energy affordability.
Sustainable development is not a set concept; it evolves over time. In the 1970s, the oil crisis gave an incentive to experiment with alternatives to fossil fuels. Today, climate change is our most pressing concern. It has become a fundamental driver of change, namely in architecture where it has incentivized significant technological development. But a sustainable built environment calls also for wider cultural changes, such as updating the curricula of students and requiring established practitioners and academics to acquire new skills and knowledge.
“Much of the responsibility for humanity’s ability to live within the limits of our biosphere is held by engineers, architects and planners”
The construction, operation and maintenance of buildings are energy and resource-intensive activities. According to the World Green Building Council, the built environment accounts for 39 per cent of global carbon emissions, 28 of which are associated with the energy required for the so-called “building operations” alone – such as heating, cooling, ventilation and lighting. The carbon emissions associated with construction account for the remaining 11 per cent. As a result, much of the responsibility for humanity’s ability to live within the limits of our biosphere is held by engineers, architects, planners, and other professions involved in the design, management, and construction of buildings.
Climate-conscious innovations
The idea of sustainable architecture is strongly associated with certain technologies, such as heat pumps, solar collectors and photovoltaic panels. Yet the transition towards sustainable design also involves embracing more climate-conscious approaches to architectural design and urbanism. These “passive design” approaches look at how fundamental decisions, such as orientation or the intelligent use of glazing and shading, can help to adapt buildings better to the local climate. They can help reduce, and at times eliminate, the reliance on heating and cooling systems.
The principles of passive design are not new. Their use is evident in the design of traditional architecture and mentioned in ancient literature. The famous Greek philosopher Socrates wrote about the relationship between climate and the shape and orientation of buildings, whereas Vitrivius, an architect of Ancient Rome, gave detailed guidance on building design for different climates.
Today, modern technologies facilitate the revival of ancient climate-responsive design tradition. One example of passive design is the German PassivHaus standard, which focuses on optimizing energy efficiency through air tightness, high levels of thermal insulation and the use of triple-glazed windows. The PassivHaus also utilizes “active” techniques of mechanical ventilation and heat recovery - indeed, a sustainable building is rarely purely passive. Most practices incorporate active systems for ventilation, heating, cooling, as well as renewable energy generation.
In hot climates, on the other hand, the primary concern is to prevent heat from entering and to reduce mechanical air conditioning use. Traditional design for hot climates can be observed in historic cities of the Middle East and the northern parts of Africa, such as Fez in Morocco and Aleppo in Syria. They are characterized by thick walls with small openings as well as shaded courtyards and streets. In the 16th-century city of Shibam in Yemen the same principles have been applied to tall buildings.
These features are in sharp contrast to the architecture and urbanism of modern desert cities such as Dubai in the United Arab Emirates and Doha in Qatar, which are dominated by modern skyscrapers. Even when provided with external shading or special glazing designed to reduce the admission of solar radiation, their demand for mechanical cooling is high. Yet alternative models of development are also being explored in the Arabian Peninsula. Masdar, a new city in Abu Dhabi that has been under construction since 2008, represents an attempt to design a modern city that draws on traditional principles of climate design while incorporating renewable energy technologies.
The hidden emissions of materials
Although building operations account for the majority of the sector's carbon emissions, the carbon footprint of the construction of buildings is not insubstantial. “Embodied carbon” of a building refers to the emissions generated during the extraction and processing of raw materials as well as transportation. Some of the most carbon intensive materials are steel, reinforced concrete and brick. The cement industry accounts for around 8 per cent of global carbon emissions; the construction sector, with its appetite for reinforced concrete, is one of its biggest consumers.
Embodied carbon can be reduced in many ways, including more efficient use of materials, decarbonizing production, and utilizing alternative, low-carbon materials. The latter has led to an increase in interest in natural resources. These include plant-based materials, such as timber or reed, and locally sourced earth-based construction techniques, such as rammed earth, compressed earth blocks, or sun-dried clay bricks. In 2021 a Swedish firm introduced a method for fabricating low-carbon steel using hydrogen produced with renewable electricity.
Recent projects around the world have demonstrated that the use of engineered timber can help reduce the reliance on steel and concrete in high-rise buildings, such as the 85.4 metre-tall Mjøstårnet tower in Brumunddal, Norway, constructed using glue-laminated and cross-laminated timber.
From a linear to circular economy
Reduction in material consumption is another key goal towards sustainability. Toward this end, we need to move from a linear economy, where building materials are used and discarded, to a circular economy where they are reused and recycled. In the circular economy the materials released during demolition are not treated as waste but as resources. This calls for construction systems that are designed to be easily disassembled for reuse.
“Reducing material consumption is key to sustainability”
Timber-framed buildings of England, Malaysia, China or Japan are traditional examples of demountable structures. In contemporary architecture, projects range from "220 Terminal Avenue", a 40-unit modular temporary housing building opened in 2017 in Vancouver, Canada, to demountable arenas used for major sports events. Another illustration of a demountable structure is the Loblolly House by American firm Kieran Timberlake – a hybrid house made up of prefabricated components that can be assembled and disassembled on site using simple hand tools.
Sustainable practice also implicates responsibility for the long-term stewardship of buildings and their materials, encompassing the creation, operation, maintenance and renewal over generations. This also relates to the retention and adaptive re-use of existing buildings, highlighting the intersection between sustainable development and architectural conservation.
Reuse rather than destroy
Adaptive reuse offers a means to avoid demolition, but also the opportunity to reduce energy consumption through retrofit. Much care is given to preservation of historically significant buildings, yet the majority of buildings are regarded as historically insignificant. Many of them undergo demolition after only 30 to 50 years. The global environmental crisis, however, forces us to question this practice. The question arises whether “climate significance” should be introduced as a new criterion for protection, alongside cultural or historical significance.
In France the architects Anne Lacaton and Jean-Philippe Vassal have demonstrated how the renewal of post-war social housing blocks can offer alternative scenarios to demolition. In Freiburg, Germany, the Bugginger Strasse 50 retrofit project of a 16-storey tower block from the 1960s reduced its heating energy consumption by 80 per cent.
Many projects in Europe and North America tend to involve technologically complex and expensive solutions, but the underlying principles of sustainable design are universal and can be adapted to different socio-economic and climatic contexts. In the 20th century, Laurie Baker (1917-2007) in India and Hassan Fathy (1900-1989) in Egypt explored the revival of traditional construction to achieve affordable, climate-adapted housing. More recently the Burkinabé-German architect Diébédo Francis Kéré and the Pakistani architect Yasmeen Lari have returned to principles of vernacular architecture to formulate a language of sustainable architecture for the global South.
By drawing on fundamental building physics, the rising vernacular trend suggests that sustainable architecture is neither dependent on complex technical solutions nor an unattainable goal reliant on future technological inventions. Sustainability requires designers to be resourceful in making intelligent use of the plethora of existing and emergent technologies and principles.
From the mud houses of the Dogons in Mali to the dry-stone constructions of Italy's Cinque Terre region, both UNESCO World Heritage sites; from Finnish wooden mökki to troglodyte houses, vernacular architecture is everywhere. This type of construction is renowned for the skill of its craftsmen, the simplicity of its means, its respect for the environment and the common sense of its genius.
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